Preparation of mercaptans



Patented Aug. 16 1949 PREPARATION OF MERCAPTANS I No Drawing.

This invention relates togmercaptans and it involves the Preparation-mt monomeric and polymeric polysulfldes.

It is an object of the invention to provide novel methods for makmgtmercaptans and derivatives 5 thereof.

The principles oftheizivention and the manner in which it is fierentiated from the prior .art will clear .from'the following description infcfifitfilniisiflfiblic for fsclienfaticuormiil e Itfidiequatidns-iilustratinithosefifinfiiiils;which The symbolicrepresentationuof the process is as follows:

TM wtumumasm ic a soluble satton ormic a iavtiymande mama-er fiil'dge to emaace' tae mam- "mano eignite mares-mesa. 3x *iie a nitrataiem PAT Application August 26, 1944, Serial No. 551,431

1 Claim. (01. 260609) etc. It combines with the'ation of the soluble or alkaline polysulfide to form the salt NaX. Instead of the cation sodium," numerous other cations may be substitutedre. g., potassium, lithium, ammonium, substituted ammonium, caesium etc. The soluble or alkaline-'folysulfide is preferably the disulfide but mayhea tri tetra-, pentaor hexasulfide or miikt'ures thereof.

Referring to Equation 2 of Case 1, the monomeric polysulfide RS'SRisYeacted withsodium hydrosulfide. Instead 6f sodium hydrosulfide, any ionizable hydrosulfide may be used and generically the reagent used here may be any ionizable sulfide, 'e. g.," hydrogn su'lfi'de, 1 sdd'iu'm sulfide, potassium sulfide,=-lithium sulfide, caesium sulfide, ammonium sulfide, substituted ammonium sulfides, calcium sulfide, barium sulfide, manganous sulfldeaetc. I

It will be seen that the reaction is a splitting or cleavage of the organic polysulfide, with sulfur as i a by-product and -it hasbeen found that the use of a sulfur acceptoris necessary to et a satisfactory reaction. :Sulfites,v e. g., isulfites of sodium, potassium, ammonium, substituted ammonium, lithium, calciumfb'arium, in fact, sulfites in general, areigoodexample oi-atsulfuz acceptoreIn :gneral any; reagent that will removesulfunfrom -.th'e"' sphere of the reaction; as fast as it 'is termed am'd"not seriousltompair*thepotencyof thea ulat oigaa c seam-a1.

="50 .fide splitti-ng =or cleavage reagent, willserve -the 213189058 of zaisulf ur acceptor.

I :Thedonizabie-sulfidesand *hydrosulfides-mreso iclosel ytrelated that they :may :be comprehended Mthmtthesgeneric =term ionizaible sulfides for 1 i1 WI'DOSEAOIjthiS invention.

When the splitting action :is=-comp1eted, -the meroa'ptan will be in the 'iorm ofra-zmercaptid'e if ionizable hydrosulfide 1 or sulfide 0f the 5 salt itypeziha'sa been iuse'd, 1 from wh-ichmercaptide the rig lmercaptem Jean be :liberated by treatment iwith 'tehifieratiire and pressuresthe reactionailso gos esaeeiiteg-eraimit fit sinenur xs attaeneu to m an sryrnuieus.

By way of example, the following specific illustration of the general formula RX may be given.

CHaX CH3 (CH2) nX where n may vary from 1 to 30 or more Y cHr=cncmx CH3CH=CHCH2X CHz=CMeCH2X MezC =CHC HzX where n may vary from 2 to 30 or more Referring again to Equation 1 the alkaline polysulfide (used to make the organic polysulfide) is shown as the disulfide. Polysulfides of higher rank than the disulfide, e. g., the tri-, tetra-, pentaand hexasulfides may be used. -There is no advantage in doing so because the excess sulfur above the disulfide rank is simply stripped off by the sulfide r hydrosulflde in Equation 2. Therefore, in Equation 1 disulfides are the preferred species of polysulfides.

Referring now to Case 2, the procedure is analogous, the chief difference being that instead of using a unifunctional organic reactant having the formula RX, a bifunctional reactant is used, i. e., an organic compound containing only-two substituents X attached to each of two carbon atoms,'respectively. As a result of this bifunctionality, an organic polymeric polysulfide, preferably disulfide is formed the splitting of which yields a monomeric dimercapto compound. Thesame sulfide splitting agent may be used. Here again, asulfur acceptor is necessary. Here again, the reaction mechanism is a general one not dependcut on th specific structure of the organic compound (within the definition given). Numerous example of bifunctional organic reactants may be seen by reference to Patrick Patents 1,890,191 and 2 ,014,166. All of the numerous bifunctional organic compounds shown in these patentsfmay 4 be used and converted into corresponding mercapto compounds.

The procedure in Case 3 is similar except that the organic compound used is trifunctional instead of bifunctional. Since it is the functionality and not the specific structure which is responsible for the generic reaction, in all of the cases mentioned, that specific structure will naturally vary widely in Case 3 as well as Cases 1 and 2 and a few specific examples of compounds XRX X zwinftrherefore Sumce, as follows:

' ,xicmomx xomgnonix x Reduced to its simplest terms it will be seen that the invention accomplishes the conversion of the X substituent into an SH group Where X is a halogen or other substituent split off by reaction with an alkaline or soluble polysulfide. By employing amixture of organic reactants having the symbol Rx, mix and xgx where R has diiferent specific structure in the several compounds; mixtures of specifically different mercaptans may be obtained;

Itwill be understood that mercaptans having a functionality greater than three (more than three SH groups) may be made, in the light of the foregoing, by choosing an organic reactant having a corresponding functionality.

To further illustrate but not to limit the methods of the invention the following detailed examples are given: l

Example I r-Htustrating Case 1 2 mols of butyl chloride are caused to react with 500 ml. of a 2-molar solution of sodium disulfide, preferably in the presence of 5 g. of magnesium hydroxide dispersed in the aqueous polysulficle solution. The mixture of the organic halide and the polysulfide are heated together for about one hour with suitable agitation to about 60 to 70 C. to cause substitution of the 1hIalogen by the disulfide group with elimination of aCl.

At the completior i'of the reaction, the dispersion of the organic sulfur compound is caused to settle out of the solution. The supernatant liquid is withdrawn and the dispersion is diluted with water to a volume of about 300-400 ml.

One mol of sodium hydrosulfide and one mol of sodiumsulfite are dissolved in theaqueous dispersion and the mixture-is heated with agitation to about 5,0.to'60 C. for an hour.

The dispersionis acidifiedto' a pH of about 6 preferably withacetic acid and the mercaptan separated by any suitable means, preferably by steam distillation in this case.

Yieldsare from to of theoretiqaLJ-J Example 2.Further illustratin Case 1 2 mols of ethylene chlorhydrin are caused to react with 500 ml. of a 2-molar solution of NazSz, no dispersant is necessary, by slow addition of the chlorhydrin to th stirred polysulfide keeping the temperature between and C. After the chlorhydrin is all in and all tendency for the temperature to rise has ceased, the temperature is raised to about 80 C. for 15 minutes, then the agitation is stopped and the heavy oil is allowed to settle out. The supernatant liquid is withdrawn and the volume restored with water.

One mol each of NaSH and NazSOa is added and the liquid heated to about to C. with agitation for about one hour. The mercapto ethanol so formed is separated preferably by steam distillation.

Example 3.Illustrating Case 2 One mol of chlorethoxyethyl chloroethyl ether, CIC2H4OC2H4OC2H4C1, is caused to react with 500 ml. of a 2-molar solution of sodium disulfide in the presence of magnesium hydroxide, by heating with agitation to from 70 to C. for one hour. The dispersed latex-like polymer is settled out of the liquid and the latex is diluted to about 500 ml. with water.

One mol each of NaSH and NazSOa are added and the heating and agitation is continued for about an hour at 70 to 80 C.

The liquid is brought to a pH of about 6 with acid-preferably acetic and the mercaptan HSCzH4OC2I-I4OC2H4SH, separated by distillation with steam or by extraction. Yields about Example 4.Illastrating Case 3 Proceed as in Example 3, except using 2 mols of the trifunctional reactant to 3 mols of NazSz and split with 3 mols each of NaSH and NazSOa.

What is claimed is:

Process of making mercaptans which comprises reacting an organic polysulfide having a symbolic formula of the group consisting of RSSR. and SSRSSR'SSR'- where R and R are alkyl and alkylene radicals, respectively, with a sulfide reagent of the group consisting of alkaline sulfides and hydrosulfides in the presence of an alkaline sulfite, the sulfide reagent and alkaline sulfite being used in the ratio of at least one mol of each to each mol of the monomeric polysulfide RSSR. and the polymeric unit --RSS respectively.

JOSEPH C. PATRICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Transactions of the Faraday Society, Patrick, vol. 32, Jan. 1936, pages 347-357.

Industrial and Eng. Chem, Martin, vol. 38, pages 1145-1149 (1936). 

